```
main :: IO ()
main = do
  (Just hin, Just hout, _, _) <-
    createProcess (proc "/usr/bin/cat" []) {std_in = CreatePipe, std_out = CreatePipe}
  hSetBuffering hin LineBuffering
  hSetBuffering hout LineBuffering
  forkIO $ getMessages hout
  sendMessages hin 5
```